Notes:
These were all over a pine stump, in big groups, in an area that has not tended to display many mushrooms, or much variety of them. There were even clumps on the ground nearby, probably growing out of the stump’s roots.

The fifth photo shows a young group on top of the stump, with yellowish gills; many of the photos focus on older mushrooms, which have a dingy grey coloring on the gills (with yellow still showing through). This color change points towards Hypholoma, and the general appearance towards H. capnoides.

Seventh photo shows the same group as the fifth photo, but as they appeared eight days later.